The Invoice in FA as a whole is not editable. Specially in case of sales of components (inventory items) it is not recommended to make invoice editable. But in case of sales of Service Items following option shall be considerable.
When we click the EditInvoice Icon on Customer Transaction Inquiry page it shall open following document with following parameters.
http://localhost/bx242/sales/sales_order_entry.php?NewInvoice=72&InvoiceNo=70
Where NewInvoice refers to the Auto Sales Order of the Invoice No 70.
While processing this document the system shall check the InvoiceNo parameter and execute the Void Routine to void the previous invoice.
This Edit option shall be available to 2 type of companies
1. Total Service Based Company. A check can be added in company setup.
2. A Company selling components but has enabled Negative Inventory in Setup.
I couldn't code it completely so if admin can consider it then it will be a good solution to all FA Users
Regards.